This invention relates generally to biocompatible implants and related devices, and more particularly to a thermal packaging unit for heating biocompatible implants.
In many surgical operations, portions of the human body are replaced by or are supplemented by various biocompatible implants. These biocompatible implants are made from a wide variety of materials including natural human bone, various nontoxic biocompatible metals, and many different types of plastics including polymer materials. In certain circumstances, it is desired to deform a biocompatible implant to conform to a given geometry of a portion of the human body prior to implantation. One method which has been suggested to deform such a biocompatible implant is to heat the biocompatible implant to a temperature where the biocompatible implant becomes malleable. Once the biocompatible implant becomes malleable, the biocompatible implant is deformed to the desired shape and then allowed to cool.
There are several methods which have been suggested to heat a biocompatible implant to a temperature where the biocompatible implant becomes malleable. In one method, the biocompatible implant is placed in a hot water bath for a sufficient length of time so as to cause the biocompatible implant to become malleable. After the biocompatible implant has been heated to such a temperature, the biocompatible implant is removed from the hot water bath and then is deformed. In another method, electrical energy is delivered to an electrode so as to cause the electrode to generate thermal energy. The biocompatible implant is then brought into a position adjacent to the electrode so as to cause the temperature of the biocompatible implant to rise. After the temperature of the biocompatible implant rises to such a temperature so as to become malleable, the biocompatible implant is deformed to the desired shape and allowed to cool. These two methods are briefly discussed in Wittenberg, J. M. Wittenberg, R. H. and Hipp, J. A.; Biomechanical Properties of Resorbable Poly-L-lactide Plates and Screws: A Comparison with Traditional Systems, J. Oral Maxillofac. Surg. 49:512-516 (1991).
While such methods for heating biocompatible implants are effective, they nevertheless have certain disadvantages. For example, the use of a hot water bath to heat a biocompatible implant often involve the inconvenience of manipulating an implant which is wet immediately prior to implantation. In addition, the use of hot water baths is complicated by steps which may be necessary to maintain sterile conditions. In this regard, the containers which are used for immersing the biocompatible implant within the hot water bath may have to be resterilized following each use. In addition, the equipment used to initially heat the hot water bath may also have to be resterilized. Finally, the use of an external heat source such as a flame or a resistance heating system is often inconvenient in the surgical environment.
With respect to the use of an electrode for heating the biocompatible implants, it will be appreciated that it is also inconvenient to maintain the sterility of the electrode in the surgical environment. Furthermore, physical contact between the biocompatible implant and the electrode may cause damage to the physical structure of the implant by locally melting the implant.
The need therefore exists for an improved means for conveniently heating biocompatible implants to an elevated temperature so as to allow the biocompatible device to be deformed.